从两列中选择SELECT not null列

Question

我有一个有两列的表,其中一列是一列,一列NULL不会,我想做的是:

SELECT (column1 OR column2) AS value

但我需要检索非null值.我觉得这可能是一个简单的问题,但任何帮助表示赞赏.

Answer 1

SELECT COALESCE(column1, column2) AS value

要么

SELECT IFNULL(column1, column2) AS value

要么

SELECT CASE WHEN column1 IS NOT NULL THEN column1 ELSE column2 END AS value

要么

SELECT IF(column1 IS NOT NULL, column1, column2) AS value